Evidence of 2 waves of Chlamydia pneumoniae infection in Gävle, Sweden, 1990-96.

Chlamydia pneumoniae is a common respiratory tract pathogen. The majority of adults have serological evidence of previous exposure. Most infections are probably asymptomatic or subclinical. Recent studies have implicated C. pneumoniae as a risk factor for the development of cardiovascular disease. It was therefore of interest to study new blood donors collected between the years of 1990 and 1996 for the purpose of delineating the epidemiological situation in the Gävle area of Sweden. Sera from all first time blood donors over a 7 y period were tested for IgG, IgA and IgM antibodies to C. pneumoniae with a microimmunofluorescence test (MIF). Donors were subjectively healthy individuals between 18 and 65 y of age, (913 M, 752 F). Exposure to C. pneumoniae, expressed in terms of specific IgG antibodies in titres of > 1/32, increased for men in 1990-92 and for women in 1990-93. There was a decrease the following year for both sexes, followed by another increase in 1994-95. IgG antibodies in titres of > or = 512, and IgA antibodies in titres of > or = 1/64, were increased in 1990-91 for men and in 1994-96 for both sexes. The prevalence of specific antibodies increased throughout the 7 y period except for women 1995-96. Men had higher antibody titres than women throughout the entire study period. The results indicate that two waves of largely subclinical infection occurred in our area over the years 1990-96.